20111210211991 has 2 divisors, whose sum is σ = 20111210211992. Its totient is φ = 20111210211990.

The previous prime is 20111210211941. The next prime is 20111210212001. The reversal of 20111210211991 is 19911201211102.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20111210211991 - 2¹⁹ = 20111209687703 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20111210211901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10055605105995 + 10055605105996.

It is an arithmetic number, because the mean of its divisors is an integer number (10055605105996).

Almost surely, 2^{20111210211991} is an apocalyptic number.

20111210211991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20111210211991 is an equidigital number, since it uses as much as digits as its factorization.

20111210211991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 31.

The spelling of 20111210211991 in words is "twenty trillion, one hundred eleven billion, two hundred ten million, two hundred eleven thousand, nine hundred ninety-one".